Check the PAN#4 output and if the correct number of blocks were cleared, then yes - Panvalet will use the additional extents if all the extents are the same volume.
The number of blocks per track are based on the blocksize specified for the PANLIB.
For example for 3390 type DASD -
BLKSIZE 27998 results in 2 blocks / track
BLKSIZE 2212 restults in 20 blocks / track
See Table of Block Sizes
for a complete list of DASD types and blocksizes